Alternaria is a common airborne fungus which frequently causes rhinitis or asthma in humans. In the studies proposed the seasonal distribution and diurnal variation of airbone Alternaria allergens will be measured immunochemically by high volume air samplers equipped with fiberglass sheets. Particular attention will be paid to determine if Alternaria allergens are associated with airborne particles small enough (less than 6 microns) to penetrate the lower airways during respiration. The second objective will be to determine more completely the biochemical, physicochemical,aand immunochemical characteristic of Alt-I, a purified allergenic fraction of Alternaria, and possibly to determine these characteristics in other Alternaria allergens. A third objective will be the development of monoclonal antibodies to purified Alternaria allergens, so as to secure larger quantities of these allergens more rapidly by affinity chromatography. These monoclonal antibodies will also be used to accomplish the fourth objective, which is to determine the source of Alternaria allergens by immunofluorescent study of Alternaria conidiae and hyphae. The fifth and final objective will be to determine the long-term clinical, immunological, and physiological consequences of Alternaria immunotherapy using a doubleblind, placebo-controlled injection program in which the immunizing agents are carefully standardized with respect to allergen content. Although immunotherapy with fungal extracts is a widely utilized clinical procedure on which millions of dollars are expended annually, such a comprehensive study of its efficacy has not been reported previously. Collectively, these studies will provide more definitive information on the source, quantity, and duration of Alternaria allergen exposure, and will also provide a more rigorous scientific evaluation of the immunological, biological, physiological and clinical effects of immunotherapy for fungal-induced respiratory disease in humans.